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    <title>Document</title>
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    <script>
        // 表达式：由数字、运算符、变量等组成的式子。
        // 有一个结果，结果称为返回值
        let age = 4444 + 555;
        age + '王者';
        age = age + '王者';
        console.log(age);
        console.log(typeof age)
    </script>
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